Nitrogen Oxide (NO2) Gas Sensing Performance of ZnO Nanoparticles (NPs)/Sapphire-Based Sensors

The interesting ZnO nanoparticles (NPs)-based sensor devices are fabricated on sapphire substrates to study the nitrogen oxide (NO₂) gas sensing performance. The postheat treatment process is not used to avoid the undesired agglomeration phenomenon. Different concentrations (0.1 and 0.01 wt%) of ZnO NPs are employed to produce the studied NO₂ gas sensors. Experimentally, studied devices demonstrate good NO₂ sensing responses $sim 100$ (at 5 ppm NO₂/air, 473 K). Especially, an extremely low sensing limit of 10 ppb NO₂/air is obtained for the studied devices. This value is superior to those of previously reported results from other NO₂ sensors. The studied sensor devices also show the advantages of low cost, easy fabrication, and compact potentiality to integrate with other high-speed and optoelectronic devices. Therefore, the studied devices give the promise for high-performance NO₂ monitoring applications.